1. Field of the Invention
The present invention relates to a side knock-type mechanical pencil provided with a push member pivotally supported to the side wall of a barrel so as to be operated to cause a sliding member to slide longitudinally for projecting a lead.
2. Prior Art
Various side knock-type mechanical pencils have been proposed. Referring now to FIG. 1 illustrating a side knock-type mechanical pencil disclosed in Japanese Utility Model Publication No. 51-17942, a push lever 22 is received in a slot 21 formed in the side wall of a barrel 20 containing a lead chucking mechanism therein, and supported at one end thereof to the barrel 20. The push lever 22 is adapted to be pushed with a fingertip to advance a lead.
When the push lever 22 is pushed or knocked, a free end 22a of the push lever 22 engages with an inclined surface 24a formed on a sliding member 24 mounted on an elongated cylindrical portion 27 of a chuck 26 connected to a lead tank 23, and advances the chuck 26 against a force of a spring 25 biasing the chuck 26 backward. As the chuck 26 is moved forward, it is opened to permit a lead to advance forward relative to the chuck 26.
Whereas there is no restrictions on the diameter of the barrels of end knock-type mechanical pencils, there is a limit to the diameter of the barrels of those side knock-type mechanical pencils. Therefore, in the prior art side knock-type mechanical pencil, the lead can be advanced by a short distance by one lead advancing stroke of the chuck which is caused by one stroke of the push lever, and hence the push lever needs to be pushed many times to advance the lead from the lead tank so that the lead can be projected, which requires a troublesome operation. If it is desired to increase the lead advancing stroke of the chuck beyond a limit, the diameter of the barrel must be greatly increased, and an increased pressure is necessary for pushing the push lever because the point of engagement of the push lever and the inclined surface of the sliding member moves down beyond the center axis of the elongated portion of the chuck.